Fracture-induced polymeric grating structures

Fracture-induced structure (FIS)1 is found in the polymeric thin film sandwiched between two relatively rigid flat plates by inserting a razor blade at one edge. FIS is a potential candidate to be a low-cost and high-throughput nanopatterning technique. FIS is a complementary set of nonsymmetrical periodic grating patterns on two plates. However, the cracking mechanism of FIS in the polymeric thin film is still not fully understood which limits its application on making desirable nanostructures. In this study, FIS gratings were observed to follow the direction of the maximum in-plane shear stress induced by external separating-load as shown in Figure 1. During fracturing, local stress state in the polymeric thin film determines the crack propagation while the variation of local stress plays a key role to deviate the orientation and/or the spatial wavelength of gratings. Gamma-irradiation effect, primary/secondary gratings and competed rupture phenomenon are also discussed in this study. A quarter of concentric circle FIS gratings are produced by means of appropriate design of the separating-load type and the shape and/or boundary confinement of the polymeric thin film. This shows that it is possible to control the FIS grating structure. The results of this study can be applied to nanotechnology such as nanophotonics and nanobiotechnology.